The present invention relates to electronic musical instruments and in particular to a register arrangement for such instruments by which tone signal generation is influenced electronically rather than manually.
Sophisticated electronic musical instruments, such as electronic organs, may comprise a large number of functional units which in various ways affect the output tone signal of the instrument. A group of such units serve to provide tone formation and effects. For example, by means of suitable filters one could impart to square or saw tooth signals a selected upper wave content thereby producing a desired tone color. Similarly by employing appropriate envelope wave circuits tremolo or vibrato, percussion, piano or other effects can be achieved. Appropriate voltage regulation may also be utilized to produce still other desired effects.
Where the instrument has fixed stops for several footages as well as sine generators operated by drawbars on the instrument, a further functional unit can serve for the combination of sinusoidal signals. These further functional units are actuated by manual selector switches (usually called "registering switches") which are connected to the corresponding functional units through appropriate conductors. A large number of selector switches are disposed in the path of the tone signal (to an amplifier which in turn is usually connected to a loudspeaker). The switches may be in the conductor connected to the amplifier or the ground return path.
In order to register such an instrument it has heretofore been necessary to actuate a large number of switches, for example, five selector switches for the fixed stops in various footages and the selector switches for any desired effects (i.e., echo, tremolo). This becomes tedious to the musician particularly if, during the performance of any particular piece, extensive changes in registration are required.
Because of the above, certain instruments have been provided with so-called "free combinations" which, by means of a manually operated switchover device connect the predetermined output of various filters in various footages with collecting points which are addressed by the switchover device. The shortcoming of this arrangement is that multiple loads are placed on the filters and tone signal sources so that a relatively low output voltage is generated. Also, in order to minimize the problem of cross talk the tone signal conductors to the switchover device must be physically short thereby causing packaging problems.
In view of the above, it is the principal object of the present invention to provide a register arrangement for electronic musical instruments which overcomes the above described problems and has a minimum effect on the tone signal.